This invention relates to tensioning apparatus for chain drive systems, and in particular to tensioning systems for use on hand powered mobile storage systems.
Certainly the general concept of providing means to tighten or apply tension to chain or belt drive systems is not novel, and in fact is probably very nearly as old as the idea of chain drive itself. There has, however, been substantial development in chain tensioning devices.
See, for example, Muth, U.S. Pat. No. 5,058,507, assigned to the assignee of the present invention. This patent sets forth a chain drive tensioner for use with a carriage that has extremely low clearances for its frame, thus having to use wheel bearings other than standard pillow blocks. The tension supplied by that structure is finely adjustable by turning a screw. It requires access to the frame beneath the carriage, though.
A chain tightener that does not require access to the frame is disclosed in Sattel, U.S. Pat. No.4,559,027, also assigned to the assignee of the present invention. The chain tightener disclosed in this patent was designed mainly for manually operated mobile storage units, and again is adjusted by rotating threaded fasteners. In this case, turning the threaded fasteners flexes or deflects the shaft on which the wheels rotate.
While these chain tighteners have functioned admirably and sold successfully, there is need for structure wherein the tension supplied is more easily and quickly adjusted. The present invention relates to improvements to the tighteners described above, and to solutions to some of the problems raised or not solved thereby.